Update headerf5-tutorial.md

I couldn't find a page called "What is application access and single sign-on with Azure Active Directory". The link provided goes to a page called "Single sign-on to applications in Azure Active Directory". 

There is a page called "Application management with Azure Active Directory", and this seems to be a better page to link to, because it actually describes more about SaaS integration with Azure AD, which is what the customer will be expecting when clicking on that link, not just SSO information.

Author: knicholasa

articles/active-directory/saas-apps/headerf5-tutorial.md

@@ -28,7 +28,7 @@ In this tutorial, you'll learn how to integrate F5 with Azure Active Directory (
 * Enable your users to be automatically signed-in to F5 with their Azure AD accounts.
 * Manage your accounts in one central location - the Azure portal.
 
-To learn more about SaaS app integration with Azure AD, see [What is application access and single sign-on with Azure Active Directory](https://docs.microsoft.com/azure/active-directory/active-directory-appssoaccess-whatis).
+To learn more about SaaS app integration with Azure AD, see [Application management with Azure Active Directory](https://docs.microsoft.com/azure/active-directory/manage-apps/what-is-application-management).
 
 ## Prerequisites